OS Cheat Sheet 2026

The 30 highest-yield OS facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. How should hazardous conditions be handled during material selection work? → Stop work, secure the area, report the hazard, and follow safety protocols
2. What is a 'wire rope' made of? → Multiple strands of steel wire twisted around a central core
3. How should hazardous conditions be handled during quality inspection work? → Stop work, secure the area, report the hazard, and follow safety protocols
4. A cargo hatch cover is primarily used to: → Provide watertight closure over the cargo hold opening
5. According to maritime fire prevention regulations, where must portable fire extinguishers be located on a vessel? → At clearly marked, designated stations throughout the vessel and readily accessible
6. What does 'deadweight tonnage' (DWT) represent? → The total weight a vessel can carry including cargo, fuel, water, and crew
7. Which document lists all cargo aboard a vessel and is used by customs authorities? → Cargo manifest
8. What code compliance requirement applies to code compliance? → All work must comply with applicable local, state, and national codes
9. How should hazardous conditions be handled during technical measurements work? → Stop work, secure the area, report the hazard, and follow safety protocols
10. What is the most critical safety requirement in maintenance protocols? → Following all applicable safety regulations and wearing required PPE
11. What is a 'heaving line' used for? → Throwing a light line to a dock or another vessel to pull across a heavier mooring line
12. What inspection procedure is essential for safety procedures? → Systematic inspection following established checklists and standards
13. What is the correct technique for an ordinary seaman advancing toward a fire with a hose? → Stay low, advance slowly while maintaining a water spray curtain
14. What code compliance requirement applies to equipment operation? → All work must comply with applicable local, state, and national codes
15. What environmental protection measure applies to safety procedures? → Proper handling, storage, and disposal of materials according to environmental regulations
16. When stowing incompatible dangerous goods, the OS should refer to which document? → The IMDG Code segregation table
17. Which class of fire specifically involves flammable liquids such as fuel oil, diesel, and paint? → Class B
18. What code compliance requirement applies to environmental standards? → All work must comply with applicable local, state, and national codes
19. How should hazardous conditions be handled during equipment operation work? → Stop work, secure the area, report the hazard, and follow safety protocols
20. Which knot is used to make a fixed loop at the end of a line that will not slip under load? → Bowline
21. How should hazardous conditions be handled during code compliance work? → Stop work, secure the area, report the hazard, and follow safety protocols
22. Which fixed fire suppression system is most commonly installed in ship engine rooms? → CO2 total flooding system
23. What inspection procedure is essential for environmental standards? → Systematic inspection following established checklists and standards
24. What environmental protection measure applies to technical measurements? → Proper handling, storage, and disposal of materials according to environmental regulations
25. During shipboard firefighting, which technique is used to apply water to walls, decks, and bulkheads adjacent to a burning compartment? → Boundary cooling — wetting surrounding structures to prevent fire spread
26. What code compliance requirement applies to material selection? → All work must comply with applicable local, state, and national codes
27. What is the primary role of an Ordinary Seaman during deck maintenance? → Assisting in cleaning, painting, and securing equipment on deck.
28. According to SOLAS requirements, how frequently must fire and boat drills be conducted on merchant vessels? → At least once per month
29. What is 'lashing' in the context of cargo securing? → Using ropes, chains, or straps to secure cargo against movement
30. How should equipment be maintained for code compliance operations? → Follow manufacturer-recommended preventive maintenance schedules